The present invention refers to biochemical deodorization or bioremediation of sediment. It describes a deodorant for treating sediments in-situ, in rivers, lakes and harbours, and the associated facilities and method.
Due to rapid development of urban areas and a relatively lagging in environmental protection measures, many rivers, lakes and harbours have been seriously polluted, thus causing such environmental problems as deteriorated water qualities, blackened sediments, suppressed ecology and serious mal-odor, etc.
Among the said environmental problems, odor is the biggest drawing much attention. The mechanism by which mal-odor is generated is described as follows: As organically polluted sediments underwater are usually in an anaerobic state, only anaerobic micro-organisms could exist and would make use of the sulfate radical in water as electron acceptor to degrade the organic pollutants. The following reaction occurs:2CH2O+SO42−+2H+→H2S↑+2H2O+2CO2 
(CH2O represents the organic pollutants)
In the process, Acid Volatile Sulfides (AVS, mainly hydrogen sulfide) which emit bad odor is produced.
In recent years, governments of different countries have started to tighten their control over sources of pollution. As a result, pollution loads to such water bodies as rivers, lakes, harbours etc. have been declining year by year. However, as pollutants have been accumulated in sediments for many past years, sediments would still emit bad odor. The problem of bad odor becomes more evident particularly during low tide, when such sediments are exposed.
Conventionally, dredging has been often regarded as a method for deodorization. However, this does not work. The reason is that regardless of how advanced and efficient a dredging technology is, the polluted sediments would inevitably disperse in the course of dredging because they are fluffy in nature. Hence, even sediment thickness can be reduced after dredging, the exposed surface areas of the odorous sediment are still not. As a result, bad odor would persist. Up to date, no in-situ deodorizing technology has been disclosed save this, which sets out an important step to deodorize sediments in-situ under water.